The present invention relates to surgical staples with two legs and a back span (crown) and at least one deformation zone in each leg to control staple deformation during installation for producing hemostasis, uniting tissues and minimizing tissue damage. In internal surgery, deformed staples must develop sufficient tissue compression to achieve hemostasis but should not so develop so much compression that excessive tissue damage results. Insufficient compression results in leakages and excessive compression results in excessive tissue damage. Tissue damage can lead to tissue necrosis, and tissue necrosis results in scar tissue and may also result in leakage. Scar tissue shrinks over time, and tissue shrinkage may require additional medical attention. Leakages may also require additional medical attention and may lead to mortality.
Several patents have issued to the Assignee of the present invention and an additional patent application has been filed, all of which disclose solutions to the aforementioned problems. These include U.S. Pat. Nos. 5,445,648; 5,667,527; 5,342,396, 5,749,896 and 09/020,162. These patents and the patent application cited above all relate to surgical staples for use in internal surgery which incorporate deformation zones, i.e., regions formed in the legs which tend to bend and deform more easily than adjacent regions of the legs when the staple is installed into tissue in order to more effectively produce tissue compression, unit tissues and minimize tissue damage. In the above-cited patents and patent applications, the intermediate regions of the deformation zones, i.e., the regions intermediate the end regions of the deformation zones, have a substantially uniform cross section. Such a substantially uniform cross section means that the disclosed staple do not adjust to tissue thickness as much as would be desirable to most effectively produce hemostasis and minimize tissue damage.
Although the staple leg deformation zones disclosed in the aforementioned patents and patent application represent a significant improvement over the prior art, farther improvement is possible if the cross sections of the intermediate regions of the deformation zones are varied along their length in such a manner as to optimize the shapes of the deformed installed staples since this controls tissue compression and affects tissue damage.
It is a purpose of the present invention to produce staples having deformation zones that vary in cross section along their intermediate regions in order that the staple can adjust to tissue thickness and density during its deformation so as to optimize tissue compression and to minimize tissue damage.
It is an additional purpose of the present invention to produce staples having deformation zones that vary in cross section along their intermediate regions so that the legs in the deformation zones so as to optimize tissue compression and to minimize tissue damage.